OULTON PARK WITH FS-3 KAWASAKI

6/24/2021

With British Superbike kicking off this weekend, FS-3 Kawasaki crew chief Ian Prestwood shows how he uses MotoSPEC to simulate and evaluate the effect of setup changes at Oulton Park.

MotoSPEC DATA EQUATIONS

The MotoSPEC interface displays the instantaneous geometry and forces with respect to a pair of front and rear potentiometer readings .

MotoSPEC Data Equations will plot these same values within the MoTeC i2 Pro interface, over full laps and allowing comparison with other data channels like brake pressure and throttle input.

MotoSPEC Data Equations can be similarly used with AiM Race Studio, Marelli WinTAX and 2D WinARace.

The image below shows the MotoSPEC interface on the left, with i2 Pro in black on the right

i2 is displaying potentiometer readings, and the chassis math channel values for Rake, Ground Trail, Swingarm Angle and Anti-squat Angle, calculated using the MotoSPEC Data Equations for the current settings. The Google track map shows the location of the bike at the apex of Brittens.

In the first column of MotoSPEC are the current settings, with a proposed setup in the middle column. In this case, Ian is interested in reducing the trail at Brittens and is looking at adding 2 mm of offset and 0.2 degrees of rake.

After examining the geometry change in the MotoSPEC interface, the changes can be reviewed over a complete lap using the Data Equations.

MotoSPEC Data Equations allow i2 Pro to calculate the chassis geometry and forces. providing a continuous picture of the geometry all around the lap.

The setup changes proposed (offset and rake increase) will not significantly affect the potentiometer readings, as they will not significantly change the wheelbase, chassis height or suspension stiffness. The recorded potentiometer readings should accurately calculate the new geometry with the proposed settings.

To identify the the chassis math channels corresponding to the proposed changes , MotoSPEC provides an easy method to modify the channel names, appending a single character to the channel names. In this case, an ‘X’ is appended to the proposed setup channel names.

Where the current setup has the ground trail channel named ‘MotoSPEC_GndTrail’, the trail channel for the proposed setup will be named ‘MotoSPEC_GndTrailX’.

The Data Equations XML file for the proposed setup imports all of it's math channels quickly into the Workspace Maths of i2 Pro.

The math channels for both the current and proposed setups are plotted in i2 and difference throughout the lap can then be easily examined.

The minimum, maximum and average values of the chassis math channels are also calculated by i2 Pro, allowing identification of new points of interests around the lap.

At the mid-corner apex of Brittens at Oulton, the Data Equations calculate the trail to be reduced from 100.2 mm to 96.6 mm at the apex of Britten’s. These are the same values calculated in the MotoSPEC interface at those potentiometer readings, confirming that the Data Equations calculations are accurate representations of the MotoSPEC calculations.

Ian can then examine the rest of the lap determine if these changes will be a net benefit over the rest of the lap, or if there are other locations where the trail is reduced too much, making the bike overly nervous or reducing rider confidence in the front on the bike.

If the reduction in trail is judged too much, a new setup and it’s Data Equations can be quickly evaluated to try to generate the same effect in Britten’s while minimizing the change on the rest of the lap.

MotoSPEC FORCE MATCHING

MotoSPEC also provides a Force Matching function to automatically solve for suspension compressions created by a difference in settings.

In the image below, the DYNAMIC READINGS preset in second column is set to ‘= Forces 1’. This tells MotoSPEC to solve for the potentiometer readings in the second column, to equal the front and rear forces in first column.

The first MotoSPEC column below uses FS-3’s ‘T21A’ link.
The second column uses their ‘IP45’ link, with 1 mm additional rear spring preload.

Again at Brittens, Ian can quickly review the new geometry that will be achieved, relative to the settings in column 1.

MotoSPEC has calculated that the rear potentiometer reading will be reduced by 1.4 mm, resulting in a higher rear ride height, with steeper swingarm angle and a reduction in trail.

By typing in a different combination of pot readings into column 1, both columns will recalculate, with column 2 solving for the new force values in column 1. In this way, Ian can quickly iterate thru other points of interest around the lap and see the simulated geometry with the new settings in column 2.

Modifying the proposed settings in column 2 will result in it's potentiometer readings being recalculated to achieve the forces in column 1.